The present invention relates to a control-key mechanism.
In the known art, a kind of control-key mechanism is used, such as, in computers, for example, video game apparatus including video game apparatus of business use or video game apparatus of personal use. In these video game apparatuses, a display screen such as using a liquid crystal display device is provided. In this display screen, a character is moved in response to an operation performed on the video game apparatus by an operator. The character is an object represented on the display screen. The operator may specify the movement of the character using the control-key mechanism such as that mentioned above.
Using the control-key mechanism, the operator may specify or may select a direction in which the character moves. The direction selected is selected from various directions, for example, 4 directions on the screen, that is, the top, bottom, right and left, or 8 directions, the top, bottom, right, left, top left, top right, bottom left, and bottom right.
Such a control-key mechanism has a construction such that the operator may control the character, via the control-key mechanism with very small force being applied to the control-key mechanism by the operator's finger so as to control, for example, the movement of the above-mentioned character displayed on the screen. This is because, for example, the operator has to control the movement of the character very frequently. Thus, if this control needed a relatively large force, the operator's finger would become tired.
The Japanese Utility-Model Publication No. 3-13951 corresponding to U.S. Pat. No. 4,687,200, discloses such a conventional control-key mechanism. This conventional control-key mechanism has a key top. A half-spherical shaped projection projects downward from a center of a bottom surface of the key top. The control-key mechanism also has a circuit substrate. In the control-key mechanism, there exists a small space between the top of the half-spherical shaped projection and the circuit substrate.
A elastic supporting member is provided so as to support a disc portion formed on the periphery of the bottom surface of the key top so that the key top is supported on the circuit substrate. Thus, the above-mentioned small space is maintained.
When the operator pushes, in a certain direction, the key top of the above-mentioned conventional control-key mechanism, the top of the half-sphere shaped projection comes in contact with the substrate. Thus, the portion where the top of the half-sphere shaped projection comes in contact with the substrate will act as a supporting point to be used for a seesaw-like movement of the key top on the substrate.
Depending on the direction in which the control-key is being pushed, the key top is tilted in a corresponding direction with the above-mentioned seesaw-like movement using the supporting point. This tilting of the key top causes a conductive rubber, provided on the bottom surface of the supporting member, to come in contact with a plurality of contacts provided on the circuit substrate. This coming in contact with the plurality of contacts, that is, a short-circuiting of the plurality of contacts results in forming a corresponding circuit on the circuit substrate.
In this construction of the conventional control-key mechanism, the following drawback may exist. When the operator operates, that is, pushes the key top in a certain direction, the top of the half-sphere shaped projection is rubbing against the circuit substrate at the portion acting as the above-mentioned supporting point to be used for the seesaw movement. This rubbing is caused by the seesaw movement of the key top on the substrate.
Such rubbing results in a corresponding friction between the top of the half-sphere shaped projection and the counterpart on the circuit substrate. Such friction may damage these rubbing parts so as to shorten a life time of the control-key mechanism.
Further, there may be a case where a relatively large mechanical shock is applied on the key top so as to cause the top of the half-sphere projection to collide with the counterpart on the circuit substrate. Such case also may damage the same parts so as also to shorten the life of the control-key mechanism.
As mentioned above, the control-key mechanism may be operated very frequently by the operator when it is applied, for example, to the video game apparatus. Such frequent operations may excessively facilitate the above-mentioned damages resulting in shortening the life of the control-key mechanism.